Article of manufacture and method of making the same



F. l.. HEvss Dec. 24, 1935.

ARTICLE 0F MANUFACTURE AND METHOD OF MAKING THE SAME FiTed Deo. l0, 1952|IIIlmIIII INVENTOR f Freal L. Hes@ BY @IMQ/JPM ATTORNEY Patented Dec.24, 1935 UNITED 'sTATEs I ARTICLE OF' MANUFACTURE AND METHOD F MAKINGTHE SAME Freas L. Hess, Somerville, N. J., assignor to Johns-ManvilleCorporation, New York, N. Y., a corporation of New York ApplicationDecember 10, 1932, Serial No. 646,597

6 Claims.

This invention relatesto an article of manufacture, particularly afriction material, and to the method of making the same.

The invention comprises the novel features hereinafter described orclaimed, and, especially, a friction element, adapted for use asautomotive brake lining or clutch facing, including a friction bindercompound and reenforced asbestos yarn or the like fabricated into a unitdisposed around. the binder compound, then pressed firmly thereinto, toform an impregnated product, and maintained in selected shape byAhardening of the binder. The invention comprises also the making of theimproved product by a method which includes forming a shaped mass ofbinder compound, braiding or otherwise fabricating yarn therearound,pressing to force the binder into intimate association with the yarn, asan impregnating material therefor, and hardening the binder.

The invention is illustrated in the drawing in which:

Fig. 1 shows-a perspective view ofl the product that is the embodimentof the invention preferred at this time, with certain parts broken awayfor clearness of illustration;

Fig. 2 shows a view of the product in the stage of being fabricated and,diagrammatically, the initial steps in the fabrication; and

Fig. 3 shows a perspective view of the product shaped into clutchfacing.

'There are shown strands of yarn l provided, suitably, with innerreenforcing wires 42 and a binder compound 3. The article shown as Fig.1 35 may be produced by braiding' the tube 4 around a shaped mass, say astrip of binder compound 5 passed to the braiding point through a guide6,

drawing the tube and enclosed binder through a forming die 1, to shapethe product roughly into a band, and then pressing the tube and enclosedbinder to form a bandgof desired dimensions, in such manner that thebind`er compound, supl plied initially in the form of the strip, iscaused to impregnato into the various interstices between the yarn inthe braided fabric.

The yarn used is preferably asbestos, reenforeed with small wires orother reenforcement that is conventional in asbestos yarn. Furthermore,the asbestos yarn may contain a certain 50 proportion of other fibers,as, for example, one part by weight of cotton or Wool spun with fourparts of asbestos. If heat-resistance or other unique properties ofasbestos are not desired, the yarn may consist of jute, flax, .or thelike.

The binder compound may be one comprising reenforcing flbers and abinder composition com-- monly used in friction materials. Thus, theremay be used a friction binder compound comprising wire-reenfo'rcedasbestos yarn in short lengths, rubber and conventional vulcanizingoxidation, pigment, and filler materials. Also,l there may be used aresinous phenol-aldehyde condensation product, a drying oil adapted tobe hardened, as by polymerization and/or oxidation,

as, for example, China-Wood or linseed oil. Or, 5

there may be used incompletely polymerized chloroprene of the empiricalformula CHzzCCl. CH:CH2, of consistency, as used, resembling that of rawrubber and adapted to be hardened, that is, toughened by furtherpolymerization.

Or, the binder compound may comprise a strip of Woven asbestos fabricand a binder composition impregnated thereinto and coated heavilythereon.

In general, the binder is preferably one that 15 is semiplastic orthermoplastic, as used initially, and adapted to be hardened and maderesilient after it is impregnated into the brous material. When thebinder is a rubber compound the hardening takes the form ofvulcanization. A drying oil, if used, is hardened by being subjected toan elevated temperature, in an oxidizing atmosphere; a phenol-aldehyderesin, of the type of bakelite, is hardened at an elevated temperature;and chloroprene is hardened by being subjected to an elevatedtemperature, say to a temperature of approximately 300 F. for a periodof time that maybe about 40 minutes. The binder may be applied in thecondition of being softened by a volatile solvent, which, if 30 used, isevaporated before the binder is hardened or as part of the hardeningprocess.

The invention will be illustrated by a speciflc product comprisingreenforced asbestos yarn and rubber binder compound and the method ormak- $5 ing such a product. There is rst made a rubber composition oftype used in friction materials. It may have the following, typicalcomposition:

Parts by weight 4 Reclaimed rubber 10 Raw rubber 15 Sulphur 9 Litharge-'I 45 Carbon black 10 Barium sulphate filler 38 Lead dust '1Non-volatile, oily, rubber softener resin and 50% heavy mineral oil) 250 China-wood nil 2 Total 0f the above rubber composition, 8 parts byweight are thoroughly mixed on rubber mixing rolls with 8 parts byweight of a macerated product resulting from cutting scrap reenforcedasbestos cloth or yarn into small units, pieces or short lengths,respectively. 'The mixture is then incorporated into the remaining 9 2parts of rub- .o

ber composition, to givea semi-plastic mixture, in conventional rubbermixing equipment, and

then is formed into sheets, as by' being sheeted between socalledsheeter rolls which are conventional in the rubber industry. The sheetthus formed is cut into strips of width which adapts the strips to beinserted into a tube fabricated as will be described hereinafter.

Reenforced asbestos yarn is fabricated loosely into a tube comprisingintercrossed strands, say into a braided tube in which thel strands ofyarn are braided in pairs and which tube contains relatively largeinterstices between the inter-j 'crossed strands permitting impregnationby the vance of the braiding point 8, to maintain the position and shapeof the strip at the time the various strands of yarn areA interbraidedaround the strip. This guide is supported suitably on rods I I. Beyondthe braiding point, the tube and the strip disposed therewithin areadvanced, as by being wound upon a conventional reel (not shown). Inbeing so advanced they may be drawn through the preliminary shaping orforming die 1, to form an irregular band I0, and then between squeezingrollers 9.

Preferably, the strip of binder compound, before being passed 'throughthe hollow form, and having the tube braided around it, is provided witha film ofv rubber cement over its surface. This may be done by passingthe strip, on its way to the hollow form, through a viscous solution ofrubber, comprising, suitably, rubber compound, of the type contained inthe strip, and a volatile solvent therefor. This cement coating softensthe strip and` facilitates the subsequent impregnation of the enclosingbraided fabric. It Will be noted,l from Fig. 2, that the strip of binder1 compound is of Width approximately equal to the' inside width of thetube.

The braided tube and the strip of binder compound disposed therewithin,is. then subjected to treatment to compress and flatten the tube andcompound into a dense, rectangular band, cause the binder to beimpregnated into the interstices in the fabric of -the tube, lsize theband tothe exact width and thickness desired, and vulcanize the rubbertherein.

If desired, a coating of binder compound, .say in the form ofcement'containing Volatile solvent, may be applied to the outside of thetube shortly before the whole is compressed. After the cement isapplied, the volatile solvent therein is allowed to evaporate before thepressing is undertaken. The pressing operation may then be made bypassing the tube, with its enclosed strip of binder compound, throughcalender rolls. These calender rolls exert a strong flattening andcompressing action, and cause the binder compound tobe squeezed throughthe fabric, on either face of the band, and into the intersticestherewithin. Further, the compression may bemade so severe as to causethe fabric in the face portion and the fabric in the back portion of theband to come 'tion compound, initially applied thus over the exteriorsurfaces of the yarn and the unitary mass 10 of compound initiallydisposed within the tube, are made integral with each other and then arehardened in situ.

The flattening of the tube represents one example of shaping the tubearound the mass of 15 friction compound disposed therewithin; shaping toother forms than a at band is intended to ybe included within' themeaning of the term flattening, so long as the tube ls shaped andstrongly compressed against the friction compound and the compound thuscaused to impregnate the wall of the tube.

After being calendered, the resulting band is v subjected to a processto harden the binder.

Thus, the rubber therein is vulcanized, suitably in a steam-heatedpressure die, which maintains or augments the condition of compressionand densication produced during the calendering.

To make a clutch facing, the product made as described but beforevuicanization may be bent edgewise into a disc, provided withrbrassstaples AI2 holding the two ends of the shaped strip in abutment, shapedmore exactly and further compressed in a pressure die, then vulcanized,either under pressure or without pressure, and then ground on the faces,to make the faces uniform and improve the frictional characteristics.

The material so made has desirable features. in addition to those thathave been indicated already. It contains a high proportion of rubber,that is, more than can be impregnated conveniently into the ordinary,tightly Woven fabric.

This relatively high proportion of rubber decreases the porosity of theproduct and minimizes the penetration thereinto of water, dirt, andother undesirable materials during exposure of the product. Although theproduct is of multiply thickness of fabric, there is as large aproportion of binder compound in the central as in the outer portions.In fact, the proportion of binder compound in the central portion isusually larger than in the outer portions, in contrast to the conditionwhich ordinarily prevails when the impregnated material is forced into awoven or braided fabric from the outside. This high proportion 55 o fbinder in the central portion and the fact that the fabric in the faceportion and the fabric in the back portion are continuous with eachother and integrally united at the two edge portions of the articleminimize the tendency of the product to 00 separate into lamin when usedunder severe conditions as brake lining or clutch facing in automobilesand the like.

The binder compound may be made without asbestos incorporated therein.yThe ibrous material in the binder compound, if used, may have the samecomposition as the yarn I.

The details that have been given are for the purpose of illustration,not for restriction, and many variations therefrom may be made withoutdeparting from the spirit and scope of the invention.

What I claim is:

1. In making an article adapted for use as friction material, the methodwhich comprises braiding reenforced asbestos yarns into a looselyfabricated tube, disposing within the tube a single shaped mass ofsemiplastic friction binder compound adapted to be hardened, applying acoating of friction compound to the outside of the band, pressing thetube and binder compound into a flat band, and thus uniting the saidsemiplastic binder and coating and then hardening the binder in situ.

2. In making an article adapted for use as friction material, the methodwhich comprises forming reenforced asbestos yarns into a looselyfabricated tube of intercrossed strands of yarn, forming a strip ofrubber binder compound adapted to be inserted into the said tube,treating the exterior of the said strip with rubber cement, to form aviscous liquid film thereover, disposing the thus treated strip withinthe said tube as the tube is formed, pressing the tube to flatten andform it into a band and force the rubber binder` compound therewithininto the interstices in the said fabricated yarn, and then vulcanizingthe rubber in situ.

3. In making an article adapted for use as friction material forautomobiles and the like, the method which comprises providing a singlestrip of friction compound, integrally fabricating therearound a tube ofintercrossed strands of yarn, applying additional friction compound tothe exterior surfaces of the said yarn, flattening the tube and stronglycompressing it to cause the lfriction compound to impregnate the wall ofthe tube and to cause the said additional l friction compound and thecompound of the said strip to become integral, and then subjecting thearticle to treatment to harden the compound in situ.

4. A friction material, adapted for use as brake lining and clutchfacing for automobiles and the like, comprising an integrallyfabricatedV tube of intercrossed strands of yarn, a unitary mass offriction compound disposed within the tube, the saidtube being in thecondition of having been flattened around the mass of friction compoundand pressed strongly thereagalnst and the friction compound beingthoroughly impregnated into the tube and securing together the face andback por-l tions thereof,and additional friction compound 5 applied overthe exterior of the said strands and impregnated thereinto, the saidadditional friction compound and friction compound in the said unitarymass being integrally united and'hardened in situ. 10 5. A frictionmaterial, adapted for use as brake lining and clutch facing forautomobiles and the like, comprising a unitary mass of frictioncompound, strands of yarn loosely braided therearound to form a tube,and additional friction 15 compound applied over the exterior of thesaid strands, the product being in the condition of having beenstronglycompressed, to flatten the tube and bring the face and back portionsapproximately into contact with each other and to cause 20 integralunion between the friction compound of the said unitary mass and theadditional compound applied originally over the exterior of the strands,and the friction compound having been hardened in situ. 25 6. A frictionmaterial, adapted for use as brake' llining and clutch facing forautomobiles andthe like, comprising a unitary mass of friction compound,strands of yarn woven therearound to form a tube, and additionalfriction compound 30 applied over the exterior of the said strands, theproduct being in the condition of having been strongly compressed, toatten the tube and bring the face and back portions approximately intocontact with each other and to'cause integral 35 union between thefriction compound of the said unitary mass and the additional compoundapplied originally over the exterior of the strands, and the frictioncompound having been hardened in situ. 40

FREAS L. HESS.

